DNA Structure and Synthesis

Question 1

Types of DNA:

Structure:

Answer 1

A form
B form - most common
Z form - 4 DNA strands with high % of G bases

• Complexed with Histones to form Chromatin

Question 2

DNA Synthesis

Helicase?
DNA Binding Protein?
Ligase?
Topoisomerase?

Answer 2

• DNA polymerase acts in 5’ to 3’, requires 4 dNTPs and Mg2+ ions
• Primer is added for the D.Polymerase to work
• At the 3’ end of primer, a dNTP and Mg2+ (cofactor) is added
• Unzip DNA strands
• Keeps strands separated
• Forms phosphodiester bonds
• Keeping DNA below replication fork loose

Question 3

RNA Synthesis:
Splicing?

Which enzyme does splicing?

Answer 3

• After first exon is cut, a cleavage forms at the branch point
• This cleavage then detaches from the next exon, allowing both axons to then bind
• Spliceosome